Enhancing the Light Extraction Efficiency in Micro‐Organic Light‐Emitting Diodes with Metalens

Abstract

Due to the total internal reflection caused by the mismatch of the refractive indices between organic layers and oxide layers within an organic light emitting diode (OLED), most of the light energy is trapped inside the device; if the size of an OLED is further limited to a few micrometers, most of the light will be lost on the side wall, which will further reduce the light outcoupling efficiency. This work intends to study the mechanism of light extraction efficiency of micro‐OLEDs with metalens. The results show that the metalens has a better optical extraction efficiency for single‐reflection light rather than requiring light to be multi‐reflected by the conventional photonic structures. As a result, it can effectively improve the light‐emitting coupling efficiency even the OLED size shrinks to 1 μm. This technique is expected to boost the efficiency in ultrahigh pixel densities micro displays required in emerging augmented reality (AR)/ virtual reality (VR), and can be extrapolated to other light‐emitting devices such as quantum‐dot light emitting diodes (QLEDs), micro light emitting diodes (μLEDs), and perovskite light emitting diodes (PeLEDs).